hahah yep yep. thanks. No worries I'm already very clear about how the IS works, but I seriously don't know how people can get confused over it.
When I said shooting from a boat, I meant i will be on a boat, and shooting people doing a sport i.e. wakeboarding. since the boat isn't going to stay still most of the time, and the use of a tripod is virtually impossible (tried and tested.), the only option is handheld shots and that's where IS will come in really really handy. Especially when doing sun-down sets where lighting gets really poor.